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| <title>StoreJanitor in Apache Cocoon</title> |
| <link href="http://purl.org/DC/elements/1.0/" rel="schema.DC"> |
| <meta content="Gerhard Froehlich" name="DC.Creator"> |
| <meta content="This document describes the usage of the StoreJanitor under Cocoon." name="DC.Description"> |
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| |
| <h1>Goal</h1> |
| <p>This document describes the usage of the StoreJanitor under |
| Apache Cocoon.</p> |
| |
| <h1>Description</h1> |
| |
| <p>The implementation is quite simple! Every implementation of a Store can register in the |
| StoreJanitor. It checks at a configurable interval if memory is running low. If low, |
| it greps via Round Robin a victim (Store) and frees xx% of all elements in this Store. |
| After that the StoreJanitor sleeps and waits for the next iteration.</p> |
| |
| |
| <h1>Configuration</h1> |
| |
| <pre class="code"> |
| <store-janitor logger="root.store"> |
| <parameter name="freememory" value="1000000"/> |
| <parameter name="heapsize" value="60000000"/> |
| <parameter name="cleanupthreadinterval" value="10"/> |
| <parameter name="threadpriority" value="5"/> |
| <parameter name="percent_to_free" value="10"/> |
| </store-janitor> |
| </pre> |
| |
| <p>The right configuration is very important, because wrong settings can cause a high system load.</p> |
| |
| <h2>Example configuration</h2> |
| <ul> |
| <li>Tomcat settings in tomcat.sh or tomcat.bat:</li> |
| </ul> |
| <pre class="code"> |
| %_RUNJAVA% %TOMCAT_OPTS% -Dtomcat.home="%TOMCAT_HOME%" \ |
| -Xmx200000000 org.apache.tomcat.startup.Tomcat %2 %3 %4 %5 %6 %7 %8 %9 |
| </pre> |
| <ul> |
| <li>StoreJanitor settings:</li> |
| </ul> |
| <p>The freememory and heapsize parameters always depend on the Xmx |
| parameter.</p> |
| <pre class="code"> |
| <store-janitor logger="root.store"> |
| <parameter name="freememory" value="50000000"/> |
| <parameter name="heapsize" value="150000000"/> |
| <parameter name="cleanupthreadinterval" value="10"/> |
| <parameter name="threadpriority" value="5"/> |
| <parameter name="percent_to_free" value="10"/> |
| </store-janitor> |
| </pre> |
| <p>It is recommended to have <span class="codefrag">heapsize</span> equal to -Xmx, especially |
| on Sun's JVM which is unable to shrink its heap once it grows above the minimum. |
| The <span class="codefrag">freememory</span> parameter should be greater than the amount |
| of memory necessary for normal application operation. |
| </p> |
| <p> The <span class="codefrag">cleanupthreadinterval</span> defines the interval |
| (in seconds)of the background |
| thread which checks memory. Also this parameter should configured wisely. |
| A too short interval can also cause a high system load. The |
| <span class="codefrag">threadpriority</span> defines the priority of the background thread |
| (1 is the lowest level and 10 the highest).</p> |
| <p> |
| The <span class="codefrag">percent_to_free</span> parameter describes what percentage of the |
| elements of each registered Store shall be removed when low on memory. |
| </p> |
| |
| |
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